Redox titrations - iodine and thiosulfate 222-223

Question 1

Explain the method of analysing an oxidising agent using iodine and thiosulfate ions, S₂O₃^2-.

Answer 1

• Iodide ions are added to the oxidising agent under investigation - a redox reaction takes place, producing iodine.
• The iodine is titrated against a sodium thiosulfate solution of known concentration. From the results, you can calculate the amount of iodine, and hence the concentration of the oxidising agent.

Question 2

Write the reaction between iodine, I₂ and thiosulfate ions, S₂O₃^2-.

Answer 2

2S₂O₃^2-(aq) + I₂(aq) → 2I^-(aq) + S₄O₆^2-(aq)

Question 3

Go through the questions on page 222-223

Answer 3

All of themm.